PLATE X. 



Walrus. 



Fig. 1. Superior surface of the brain (a) of Trichechus rosmctrus ; the ends of the 

 olfactory bulbs are seen anteriorly, and the pineal body is visible posteriori)' 

 between the two diverging hemispheres. The pineal body has been filled in 

 from brain c, by K. M. Scott, M.B. 



Fig. 2. Inferior surface of the same brain from which the pituitary body drawn in 

 fig. 6 had been removed. The sensory root of the right 5th nerve has the 

 Gasserian ganglion connected with it. The vorticose fissure in the hemi- 

 sphere of the cerebellum is well seen. The cranial nerves behind the 8th 

 had been torn off. The shape of the medulla oblongata was restored from 

 brain c. 



Fig. 3. Profile of the left hemisphere of the same brain. 



The above figures were drawn from nature by Professor Richard Caton. 



Fig. 4. Anterior end of the left hemisphere of the cerebrum of brain c, to show the 

 crucial fissure. 



Fig. 5. Tentorial surface of the left hemisphere of the same brain, reduced. When 

 compared with fig. 3, PL IX., several modifications in the splenial fissure 

 and adjacent convolutions will be seen. 



Fig. 6. Inferior surface of the pituitary body divided into four lobes. 



Fig. 7. Profile view of the pineal body, epiphysis cerebri. 



